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NIGHT VISION GOGGLES. ENABLING LEARNING OBJECTIVE: # 6. Action: Discuss the Principles of Night Vision, NVG General Characteristic. Condition: In the classroom setting we will discuss, Principles of Night Vision, NVG General
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ENABLING LEARNING OBJECTIVE: # 6 Action: Discuss thePrinciples of Night Vision, NVG General Characteristic. Condition: In the classroom setting we will discuss, Principles of Night Vision, NVG General Characteristic, AN/PVS-5, AN/PVS-7 NVG and Driving Techniques/Procedures Standard: Discuss IAW TC 21-305-2 Training Program for Night Vision Goggle Driving Operations, FM 21-305 Manual for Wheeled Vehicle Driver, & AR 600-55 The Army Driver and Operator Standardization program
INTRODUCTION: q This lesson is designed for familiarization purposes only, and it is not included in the final written examination. However, a quiz is to be administered. Although not critical for accomplishing the objective of the course. (Student should have a working knowledge of the basics of vision/night vision before receiving and applying any instruction on night vision goggles).
VISION • This is the most important sense you use while driving. It is the sense that makes you aware of the position of your vehicle in relation to the road. You need good dept perception for determining height and distance, good visual acuity for identifying terrain features and obstacles, And good night vision techniques for efficiency in night operations.
NIGHT VISION GOGGLE DRIVING OPERATIONSNight Operations Depth Perception Height and Distance Visual Acuity Terrain Features & Obstacles Night Vision Techniques Effective Night Operations
NIGHT VISION GOGGLE DRIVING OPERATIONSAnatomy of the Eye • The CORNEA is the clear, protective part of the eye that • covers the iris and pupil
NIGHT VISION GOGGLE DRIVING OPERATIONSAnatomy of the Eye 2. The IRIS is the colored portion of the eye
NIGHT VISION GOGGLE DRIVING OPERATIONSAnatomy of the Eye 3. The PUPIL is a hole in the center of the iris. The size of the pupil varies with the amount of light entering the eye. That is, it gets smaller with increase
NIGHT VISION GOGGLE DRIVING OPERATIONSAnatomy of the Eye 4. The LENS can change shape to focus on objects at different distances from the eye.
NIGHT VISION GOGGLE DRIVING OPERATIONSAnatomy of the Eye • The RETINA is the lining at the back of the eye where the image is formed. The picture seen by the retina is sent to • the brain along the optic nerve.
HOW THE EYE WORKS: • LIGHT ENTERS YOUR EYE THROUGH THE PUPIL. THE AMOUNT OF LIGHT ENTERING THE EYE IS CONTROLLED BY THE IRIS. THE LIGHT PASSES THROUGH THE LENS, WHICH FOCUSES IT ONTO THE RETINA AT THE BACK OF THE EYE. THE PICTURE SEEN BY THE RETINA IS UPSIDE DOWN AND THE BRAIN TURNS IT RIGHT WAY UP
VISUAL ACUITY • THIS IS HOW WELL YOU SEE. IT IS DETERMINED FOR EACH EYE BY READING A STANDRD EYE CHART. A SHORT HAND NOTATION RECORDS ACUITY, WITH NORMAL RECORDED AS 20/20
NIGHT VISION GOGGLE DRIVING OPERATIONSTypes of Vision PHOTOPIC DAYLIGHT HOURS or when a high level artificial light exists MESOPIC DAWN, DUSK, MID-LIGHT levels a reduction in color vision and visual acuity occurs as the light level decrease SCOTOPIC NIGHTIME HOURS visual acuity decreases to 20/200 or less and total loss of color vision NVG VGT 13
VISUAL PROBLEMS AFFECTING NIGHT VISION • PRESBYOPIA • NIGHT MYOPIA • ASTIGMATISM
PRESBYOPIA • The inability of the eye to focus sharply on nearby objects, resulting from hardening of the lens. • PRESBYOPIA is common in individuals over 40 • years of age. This can be corrected with certain • types of bifocal lenses.
NIGHT MYOPIA • A visual defect in which distant objects appear • blurred because their images are focused in front • of the retina rather than on it; nearsightedness. • Special lenses can be prescribed to correct this.
ASTIGMATISM • A refractive defect of the lens that prevents • focusing of sharp, distinct images. For example, • if you focus on power poles, the wires will be out • of focus in most cases. Your horizontal and • vertical focusing is not equal. It can be corrected • with prescription eye glasses.
DARK ADAPTATION • This is the process by which your eyes increase • their sensitivity to low light levels. Maximum • dark adaptation is reached in about 30-45 minutes. • Exposure to a flare or lightning may require 5-45 • minutes for night vision recovery. It takes about • 2 minutes to return to dark adaptation after using • NVG’S.
NIGHT TACTICAL PRECAUTIONS • Avoid areas of high intensity light. • Never use your headlights or 4-way flashers. • Know your route. • Quickly warn other traffic in cases of emergency • by using your tactical flashlight or Chem-light. • Understand the limitations and capabilities of the • NVG’S. THIS IS THE KEY TO HANDS ON • TRAINING.
NIGHT VISION GOGGLE DRIVING OPERATIONSSelf-Imposed Stresses • Smoking • Alcohol • Fatigue • Nutrition • Physical Condition • Sleep NVG VGT-04
Smoking: The smoker effectively reduces his/her night vision ability by 20% • Alcohol: This impairs both coordination and judgment. • Fatigue: When you tired, you are not mentally alert; fatigue will slow down your response to night situations that require immediate reaction. • Nutrition: Hunger pains lead to distraction and a shortened attention span. Failure to eat foods that provide sufficient vitamin A (eggs, cheese, carrots) can reduce night vision.
Physical Conditioning: You should exercise daily. Good physical conditioning will help you conduct night driving with less fatigue. However, too much exercise in a given day may leave you too tired. • Sleep: Night driving is more tiring and stressful than day driving. Therefore, it is important to get enough rest before driving.
NIGHT VISION GOGGLE DRIVING OPERATIONSNight Vision Scanning Techniques Are important in object identification at night. Scan from right to left or right to left, using a slow regular scanning movement.
IDENTIFICATION BY SHAPE: • Because your visual acuity is greatly reduced at night, Objects must be identified by their shape or outline. Being familiar with the architectural design of structures common to your area will help.
NIGHT VISION GOGGLE DRIVING OPERATIONSDepth Perception • The quality of seeing objects as • three-dimensional solids in space. • This aids the quality of seeing objects as three- dimensional solids in space. Perhaps it gave our tree-dwelling forefathers an edge when they swung from branch to branch. They knew exactly where in the space that next branch was located. NVG VGT-25
NIGHT VISION GOGGLE DRIVING OPERATIONSDistance Estimation/Depth Perception NVG VGT-26
NIGHT VISION GOGGLE DRIVING OPERATIONSSources of Ambient Light • The Moon • Background Lighting • Artificial Lights • Solar Lights • Lasers NVG VGT-27
Sources of Ambient Light 1. MOON: The moon provides the greatest source of ambient light at night. Light from the moon is brightest when the moon is at its highest point in the sky. 2. BACKGROUND LIGHTNING: Besides the moon, other natural light sources contribute to night brightness, such as the aurora (northern lights in the Northern Hemisphere) and starlight.
Sources of Ambient Light (Continued) 3. ARTIFICIAL LIGHTS: Lights from cities, cars, fires, and flares are sources of illumination. 4. SOLAR LIGHT: This light is usable for certain periods following sunset and before sunrise. 5. LASERS: Lasers can affect the performance of the naked eye or night vision devices.
NIGHT VISION GOGGLE DRIVING OPERATIONSWhat are Night Vision Goggles Night Vision Gogglesare devices that make an object more visible during periods of low light levels. Their performance is directly related to the amount of light available, such as starlight and moonlight. NVG VGT-30
NIGHT VISION GOGGLE DRIVING OPERATIONSAdvantages Better view of the surrounding area and object identification at night NVG’S make it possible to: Read Patrol Provide medical aid Drive Walk Observe the enemy At night without the help of lights NVG VGT-31
Performance is reduced in rain, haze, fog, snow or smoke. Visual acuity is reduced. Limited field of view. Reduced depth perception. Overconfidence. Focal range. NIGHT VISION GOGGLE DRIVING OPERATIONSDisadvantages NVG VGT-32
GENERAL DISADVANTAGES: • NVG performance is reduced in rain, haze, fog, snow, or smoke. Also, NVG do not magnify images viewed through the tubes. An object viewed through the goggles at night will be the same size as if it were seen during the day without the goggles. Objects that are difficult to see during the day with the naked eye are also hard to detect at night with NVG.
QUESTION: • NVG’S make an object more visible at night by__________ A. Magnifying objects B. Intensifying the amount of available moonlight/starlight. C. Using the NVG’S infrared light feature.
The performance of NVG’S is directly related to the amount of available light, such as star- light and moonlight. However, NVG’S are not affected by rain, haze, fog or snow. • A. TRUE B. FALSE
A halo around artificial lights as seen through the goggles is an indication of______ A. Visibility restrictions. B. Low battery power. C. A visual illusion.
How can drivers compensate for their reduced field of view? • By understanding the principles of night vision. • B. By understanding the limitations and capabilities of the device. • C. By using a slow, continual scanning pattern.
NIGHT VISION GOGGLE DRIVING OPERATIONSInfrared Illuminator The IR (INFRARED) ILLUMINATOR makes the NVG an active system capable of being detected by THE THREAT.
VIEWING CHARACTERISTIC • The field of view with the NVG’S is 40 degrees, compared to 200 degrees unaided. • NVG’S decrease depth perception at distances less than 20 feet or greater than 500 feet. • The focal range of NVG’S is 10 inches to infinity.
OVER CONFIDENCE • Overconfidence is a main fault associated with NVG use. After wearing the device for only a short time, you may feel you have complete visual acuity and depth perception when in fact you do not. The ability to drive with NVG’S is developed through training. The more you drive with goggles, the more you learn about them. As a result, you gain confidence in your ability and the capability and limitations of the device.
QUESTION: • The best range for depth perception and distance estimation when wearing goggles is less than 20 feet or greater than 500 feet. • A. TRUE B. FALSE
The field of view as seen through the goggles is limited to___________. A. 30 degrees C. 45 degrees B. 40 degrees D. 50 degrees
The objective focus is used to focus on objects from_______________. A. 1 foot to infinity. B. 10 inches to infinity. C. 20 to 500 feet.
NIGHT VISION GOGGLE DRIVING OPERATIONSGeneral Characteristics • Single-color Viewing • Monochromatic Adaptation • Dark Adaptation • Spatial Disorientation NVG VGT-44
SINGLE COLOR VIEWING: • All objects viewed through the NVG’S will appear green. NVG’S do not provide for color discrimination. As a result, it is difficult to distinguish between certain objects or features. Dark areas will appear black and light areas will appear white. Shadows, for example, are difficult to distinguish from puddles of water, walls ditches, and vice versa when viewed through goggles at night.
MONOCHROMATIC ADAPTATION: • MONOCHROMATIC ADAPTATION: (One color) Adaptation happens upon reentering a high ambient light environment after wearing the NVG for an extended time. You may experience a tint or discoloration of objects viewed with the unaided eye. This is a normal physical reaction that causes no discomfort and disappears in about 2 minutes.
DARK ADAPTATION • DARK ADAPTATION: Under ideal conditions (total dark adaptation before NVG use & removal of NVG’S in a dark environment), you can expect to regain full dark adaptation in about 2 minutes.
SPATIAL DISORIENTATION • SPATIAL DISORIENTATION: Dizziness and nausea may be caused by driving with one tube focused inside the vehicle and the other focused outside the vehicle when wearing the AN/PVS 5 series goggles. Use your assistant driver to help you with objects inside the cab of the vehicle.
Amount of ambient light. During periods of high ambient light, in a low light area, resolution is improved and objects can be identified a greater distances. Visual acuity (the accuracy with which an object is seen) with NVG’S will never be as good as it is with the naked eye during daylight conditions.Again, NVG performance is directly related to the